We hope to e above to extend our new chemical method of DNA sequencing so as to be able to sequence between 100-150 bases from any P32-labelled 5' end. We shall be applying this method to extensive sequencing of the repressor gene itself as well as the promoter and the promoter mutants of that gene. We shall also be sequencing regions around the early promoters of phage T7. We hope to be able to apply the dimetylsulfate techniques to studying the interaction of the RNA polymerase with DNA to delineate the binding site for this protein both in static and kinetic terms as to which bases are essential for the polymerase to approach DNA to find the promoter. We shall pursue the construction of plasmids creating new operator polymers. We are also in a position to clone chemically synthesized operator and reconstruct, probably by the use of DNase followed by the fusion techniqus, new small sequences representing the operator region, or modified operators, that we can clone and grow in large amounts. The technology we are developing also immediately gives us a way of fusing promoter-operator regions on defined pieces of DNA to create delibrately genes in which specific genetic regions are put directly under control of the lac promoter and operator. We have begun work toward crystallization of the complex of repessor and specific DNA fragments. BIBLIOGRAPHIC REFERENCES: Gilbert, W., Gralla, J., Majors, J., and Maxam, A., "Lactose Operator Sequences and the Action of Lac Repressor" Protein-Ligand Interaction, ed. G. Blauer, H. Sund, Walter de Gruyter pub., New York 1975.